Marín-Suárez Marco, Peltonen Joonas T, Golubev Dmitry S, Pekola Jukka P
Pico group, QTF Centre of Excellence, School of Science, Department of Applied Physics, Aalto University, Aalto, Finland.
Moscow Institute of Physics and Technology, Dolgoprudny, Russia.
Nat Nanotechnol. 2022 Mar;17(3):239-243. doi: 10.1038/s41565-021-01053-5. Epub 2022 Jan 20.
Single-electron transport relates an operation frequency f to the emitted current I through the electron charge e as I = ef (refs. ). Similarly, direct frequency-to-power conversion (FPC) links both quantities through a known energy. FPC is a natural candidate for a power standard resorting to the most basic definition of the watt: energy emitted per unit of time. The energy is traceable to Planck's constant and the time is in turn traceable to the unperturbed ground state hyperfine transition frequency of the caesium 133 atom. Hence, FPC comprises a simple and elegant way to realize the watt. In this spirit, single-photon emission and detection at known rates have been proposed as radiometric standards and experimentally realized. However, power standards are so far only traceable to electrical units, that is, to the volt and the ohm. In this Letter, we demonstrate an alternative proposal based on solid-state direct FPC using a hybrid single-electron transistor (SET). The SET injects n (integer) quasi-particles (QPs) per cycle into the two superconducting leads with discrete energies close to their superconducting gap Δ, even at zero source-drain voltage. Furthermore, the application of a bias voltage can vary the distribution of the power among the two leads, allowing for an almost equal power injection nΔf into the two. While in single-electron transport current is related to a fixed universal constant (e), in our approach Δ is a material-dependent quantity. We estimate that under optimized conditions errors can be well below 1%.
单电子输运通过电子电荷e将操作频率f与发射电流I联系起来，即I = ef（参考文献）。类似地，直接频率到功率转换（FPC）通过已知能量将这两个量联系起来。FPC是基于瓦特最基本定义的功率标准的自然候选者：单位时间内发射的能量。该能量可追溯到普朗克常数，而时间又可追溯到铯133原子未受干扰的基态超精细跃迁频率。因此，FPC提供了一种实现瓦特的简单而优雅的方法。本着这种精神，已经提出以已知速率进行单光子发射和检测作为辐射测量标准并通过实验实现。然而，到目前为止，功率标准仅可追溯到电气单位，即伏特和欧姆。在本信函中，我们展示了一种基于使用混合单电子晶体管（SET）的固态直接FPC的替代方案。即使在零源漏电压下，SET每个周期也会将n（整数）个准粒子（QP）注入到两个具有接近其超导能隙Δ的离散能量的超导引线中。此外，施加偏置电压可以改变两个引线之间的功率分布，从而几乎可以向两者注入相等的功率nΔf。在单电子输运中，电流与一个固定的通用常数（e）相关，而在我们的方法中，Δ是一个与材料有关的量。我们估计在优化条件下误差可以远低于1%。
